I am using Firefox Browser 78.0.2 (64-bit) on macOS 10.15.5 (19F101). I enabled all the features in the "Logins and Passwords" section of Preferences/Privacy Security. This resulted in Firefox remembering and auto-filling usernames and passwords as expected. It would ask me for the master password only once for every browser restart, i.e. if I close all the browser windows. If I keep the browser running it seems it'll happily fill in my passwords without ever again asking for the master password. I do not think this safe enough. How do I make the browser ask for the master password after a certain time, even if I don't restart the browser? I did a bit of research and I found the '''signon.masterPasswordReprompt.timeout_ms''' parameter under about:config. I don't know if I misunderstood the purpose of this parameter or it is just broken but this parameter ''does not'' set the master password timeout in milliseconds. Its default value is 900000, which would be 15 mins. The browser most definitely does not ask for the master password after 15 mins. I tried to set this value to various smaller values to basically no avail. One time I did manage to get a master password prompt without restarting the browser but I can't reproduce this so I am not sure what caused it. I would appreciate any help or pointers!